A background screen or a reference background screen is required for detecting the shape or motion of a person. That is, a related art lumps each part of body by using the difference between the reference background screen (or the background screen) and a current screen, and configures a human body model with each lump of body parts. For detecting a human body model or the shape or motion of a person, alternatively, the related art extracts feature points and calculates three-dimensional positions for each of the extracted feature points.
Accordingly, the related art requires the background screen or the reference background screen for detecting the shape or motion of a person. In the related art, it is substantially impossible to detect detailed motions such as hand postures, and much time is taken for calculation.